Seems to me that you’d want the brightly colored layer underneath, so the absence of a tool makes a big screaming reminder to replace it. When all your tools are put away, who cares if the underlying layer’s a bit dirty? And when one’s missing, the reminder will be more important than the smudge.

Spray adhesive is the preferred method of attaching foam to just about anything, by the way. 3M makes some good products, but if the bond isn’t critical, you can get more adhesive for cheaper by looking in the textured-coatings section of the paint aisle at your local big box.