Batman on Film has a spy report that discusses the suit’s color:
Batfleckâ€™s Batsuit is steel grey and black. Itâ€™s mostly made of foam rubber even though it appears to be â€œcloth.â€ It has the muscles built into the suit (which I think is supposed to be â€œarmorâ€ under the â€œclothâ€ bodysuit.
Being grey and black would fit in with the suit being inspired by Jim Lee’s New 52 design.
The foam rubber thing doesn’t make much sense in the light of what Kevin Smith recently said on Fat Man on Batman, which is that the suit is cloth. If you remember, Smith claims to have given Ben Affleck a big hug when he saw him in the suit. That means he actually touched the suit. If someone who touched the suit said it was cloth, I’d believe that over someone who hasn’t.