My cat always gets brown feet from the litter we use. Any suggestions?

We use co-op own brand lightweight, which she likes and we can afford. Her paws get very brown and she cant seem to get them clean, regardless of how often she washes them. She then leaves footprints everywhere. Can anyone think of an alternative that she wouldn't turn her nose up at or a suggestion where we can stop her getting brown paws. (She's a house cat so please don't suggest going outside.)