It seems that with Zbrush 3.5 the grey color of masked areas of models is not quite as dark of a grey as it used to be. That’s all fine and good, but I was wondering if there was some way to change that color at all. For example, if I was working on a model that had the “BasicMaterial” applied to it with a white color, I would like to be able to see my masked areas with a blue color, or maybe a red. I looked all through the color settings but saw nothing about it. Am I just missing it? 
Thanks!
Preferences> Edit> “Masked Object Dimming” controls how dark/Light a masked area is.
I am not aware any way to control the color of the mask display, but you can always create a texture of the color you wish, and create a mask from that (explore the “Mask by” options in the masking palette.)
The “Masked Object Dimming” is enough that I think not being able to change the color won’t bother me so much. 
Thanks for the info, I never would have thought to look under Edit.
Awsome tip! I was looking for this too! ty!