Any FO in the FO Palette that has a small Settings while in the upper right corner can be colorized. Add that FO to your Sagan to continue the colorization process.
First, select the FO and hold until the FO appears to have a grid over it.
A menu opens in the lower third of the screen with multiple options.
opens the FO Settings palette on the right side of the screen.
opens a color wheel that allows changes to brightness and color.