They are white when alive, but get stained after death when their body breaks down in the colon, usually tan or brown. Mine usually came out white cause I caught it early and killed them with a 2.5 month garlic and herb regimine.

Not sure about the pink color, but it could be picking up colors from food also. I have a friend who ate 2 green smoothies a day, and hers came out green and/or with a green stripe down their intestinal track.