As you surmised it highlights the key bindings for the game. The 'number' keys across the top that are for each 'army' are green. ESC is red for menu, F1, F2 idle engineer, idle factory and so on. The rest of the keys that are not bound are kind of a shimmery silver ice like the game logo.
You could also use timers for the key binds to indicate things like cool downs for orbitals. But that kind of functionality would require the Devs.
And it is a new toy so even though I can get chroma for the things like 'word', doing 'that' on the game machine... just wrong, very, very wrong. 
