On a Pc, you can VERY QUICKLY make a keyboard shortcut that will change your font color to whatever color you last used.

1. Go to the Customize tab of Options.
2. Near the bottom of the dialog box, click the button to customize keyboard shortcuts.
3. Under Categories, choose Home tab.
4. Under Commands, scroll to FontColorPicker.
5. Click inside the 'Press new shortcut key' text box and type a keyboard shortcut.
6. Then click the Assign button.

Every time you press that key combo, you will revert to the last-used color.

If you choose a key combo that it is currently in use, it will be overwritten by this new task/key combo.