I often have to check layer by layer to see where I “put” my color data while on a long sculpt, I turn off one layer at a time to see if I accidentally colored in a layer that is only supposed to have sculpting data in it I would love a quick way to glance and know where to even look!
could use 
maybe next to the layer title?
(since color layers rely on layer order but sculpt layers I often duplicate the layer and remove color on one and sculpt detail on the other for simplicity in future)