Aphex Twin's style?
Aphex Twin himself really has no style; he is above style. Richard D. James is, in the end, a mood; not a style. And so if you look at his records you realize that in some vague, flippant way, each one is about someone else's style. Not using that style, of course, but perverting it; tearing it apart, ripping out the soul of the musical methods and styles involved and making it his own, making it wholly a part of the Aphex Twin, with only the vaguest echo of what was originally there. Not copying or paying tribute to others in any way, but destroying; slashing out the heart of a genre, and recording the digital screams as it falls dead to the ground.

Every single one of Aphex Twin's albums has a totally different sound. Some have looked at this fact and said it is because RDJ's scope rises above any particular genre, has more depth than can be fit inside a cd case, and so in order to show his skill to the world RDJ has been forced to make each album one particular slice of his talent; one particular genre.

I personally suspect that he is doing parodies.

I personally suspect that he is doing (in some ethereal, cosmic way..) to musical paradigms what weird al does to lyrics. That each album is simply him looking at a type of music, saying "no, no, that's all wrong.." and then slashing the type up, rearranging the pieces into a blissful incoherent sonic soup, and then stepping back and smiling from the knowledge that he can do someone else's style better and more innovatively than they can.

That every time someone listens to Girl/Boy song and thinks "hm, that sounds just a little bit like Goldie", that somewhere, Richard D. James is laughing hysterically.
Looking at things this way:

This may, of course, be misinterpretation, but if so it's certainly valid misinterpretation. If you can strip away the tiny toss-off stylistic references in each album, you wind up with at the core what is among the most creative music ever made; and if you can listen to it in the right way, most of Aphex Twin's music is actually hysterically funny. It's extremely rare to see music that can express humor without any lyrics and without being the least bit goofy (the only other artist i've ever seen pull this off is Trent Reznor.. And by the way, maybe the best example of how RDJ can wear others' techniques as interchangeable skins comes on NIN's Further Down the Spiral remix album, where you can find two tracks created by Aphex Twin. The tracks are so brilliantly and uniquely Aphex that once you notice who did them, it seems impossible that anyone else could have done those tracks, but until that point it meshes so wonderfully with the rest of the album that you don't notice the artist has changed..), but Aphex does it wonderfully, and most amazingly, subtly. Whether laughter is the intended response to the Come to Daddy video will never be known, but i do know it works that way.

Particularly interesting from this perspective is Drukqs, since it seems to be Aphex Twin's take on IDM. This is interesting because IDM as a movement was essentially indirectly started by Aphex Twin. So what we have here is Aphex Twin's stylized take on Warp Records' stylized take on Aphex Twin, just kind of a look, you kids, I can still do this better than you thing.

Perhaps this would be a good place to suggest you read The Official Unofficial Aphex Twin FAQ.