I'm not going to waterproof my pair. In fact, for now I'm not going to do anything to them. In a few months I'll use Obenauf's on them.
I'd use Sno-Seal if you want to waterproof them but I'm not aware of a way to waterproof without changing the color darker. It's just how it is. If you want them to retain their original color, leave them in the closet and never wear them.