GUISkin or otherwise - Once clicked, button stays same color

I have buttons in a SelectionGrid. Once each button is selected or otherwise activated, I'd like to have it stick to the same color, and not switch back to the normal color. Do I need to create a new GUISkin?

This is my method so far (does not seem very efficient)

Initiate set of 10 buttons (2x5) as selection grid.

Upon clicking, convert to individual buttons, so that once clicked, each button stay the same active color, even when others in the set are clicked. (By default, the selection grid buttons will only show the active current one, as different color than the other non-clicked.)