sine qualitate bonum,
sine quantitate magnum,
sine indigentia creatorem,
sine situ praesentem,
sine habitu omnia continentem,
sine loco ubique totum,
sine tempore sempiternum,
sine ulla sui mutatione mutabilia facientem,
As he notes, Augustine is going through Aristotle's categories: God is to be understood as good (without quality), great (without quantity), creator (without need), present (without position), containing all (without having), wholly everywhere (without place), sempiternal (without time), acting on changeable things (without being changed), in no way affected. Thus Augustine is saying that God transcends the categories.
It's noteworthy, though, that Augustine does not here mention the category of substance, and he mentions only part of the category of relation or relatedness (instead of mentioning relatedness as such, he mentions indigentia, need or lack). This can scarcely be an accident; a significant portion of the De Trinitate is concerned with how substance and relation terms apply to God, since you need those kinds of words to talk about the Trinity. (He does not, of course, think they apply to God in the way they apply to creatures, which is why he has to discuss them at such length.)
This is not the only passage in which Augustine talks about the categories; the topic comes up in his Confessions (Book IV, Chapter XVI), as well:
And what did it profit me that, when scarce twenty years old, a book of Aristotle's, entitled The Ten Predicaments, fell into my hands — on whose very name I hung as on something great and divine, when my rhetoric master of Carthage, and others who were esteemed learned, referred to it with cheeks swelling with pride — I read it alone and understood it? And on my conferring with others, who said that with the assistance of very able masters — who not only explained it orally, but drew many things in the dust — they scarcely understood it, and could tell me no more about it than I had acquired in reading it by myself alone? And the book appeared to me to speak plainly enough of substances, such as man is, and of their qualities, — such as the figure of a man, of what kind it is; and his stature, how many feet high; and his relationship, whose brother he is; or where placed, or when born; or whether he stands or sits, or is shod or armed, or does or suffers anything; and whatever innumerable things might be classed under these nine categories, — of which I have given some examples — or under that chief category of substance.
Here we learn that, at about the age of 20, Augustine read (in Latin translation, probably that of Marius Victorinus) Aristotle's Categories themselves, and that despite being warned that it was a difficult book, thought it was fairly straightforward and obvious. The book has some significance for Augustine's theology, as he goes on to say:
What did all this profit me, seeing it even hindered me, when, imagining that whatsoever existed was comprehended in those ten categories, I tried so to understand, O my God, Your wonderful and unchangeable unity as if Thou also had been subjected to Your own greatness or beauty, so that they should exist in You as their subject, like as in bodies, whereas You Yourself art Your greatness and beauty? But a body is not great or fair because it is a body, seeing that, though it were less great or fair, it should nevertheless be a body. But that which I had conceived of You was falsehood, not truth — fictions of my misery, not the supports of Your blessedness.
Augustine, of course, tells us elsewhere that he had difficulty overcoming the idea that God is a like a body, and this gives one way in which he did have this difficult -- thinking that everything fell under the categories, he tended to think about God as if God were a subject that participated in goodness, greatness, etc., rather than being good and great simply by being God.