Theres a fabric cleaner product called Blue Magic. You can get it at any auto parts store like Autozone or Pepboys. It honestly works magic. Ive used it on the last three cars I have owned an all sorts of different fabrics and I have always been impressed with its ability to remove any stains and not leave any resedue (spelling?) or discolorations. I recently used it to clean up chunks of a candy bar someone left behind in my back seat that melted into the fabric. It came right out of the odd WRX fabric material.

Good Luck!