Their Ribbon code assigns the keystrokes, adapting to what you've put in the Quick Access Toolbar. Press and release Alt to see what you need to type next.
With Font Color.png
With nothing other than Font Color using F in the Quick Access Toolbar, I get Alt F N for Font Color and Alt F O for the Format Ribbon. From the Format Ribbon you can continue on until you get to the command you want.
No Font Color.png
Without a command that uses F in the Quick Access Toolbar there's no conflict, so you can get to the Format Ribbon with just one letter.
Ideally all of the context menu items would have had an entry in a Ribbon as well, but it is what it is.
Hope this helps.