Black is Best for this Design
Using different colors are a common question with this type of design. But, only black with white would work with this design. White with black would be visible, but it wouldn't show the shadow effect that it is meant to. It looks like gray is being used show the shadow fading.
BTW, all colors fade or turn, including white. Because cloth is darker and must be dyed, including white. For stains and fading, ash tends to be best.
But, this design Rocks!