I can change the Icon font and Icon font size through the control panel on mine but font color is always an unavailable option. Fonts are in Control Panel ->Display->Appearance->Advanced..... But like I say the colors option is greyed out and unavailable. you can bold or italicize but no color option.
Which OS are you using?
If you really want to do it I would suggest creating your own Icons that have the label built into the icon maybe.