https://www.dropbox.com/s/dqnm02pth5313sd/Quake.fgd
This uses the 0-1 colour scale.
However, in order to read future fgd's out of the box, without having to convert by hand, you might want to consider reading their native 0-255 rgb format.
In regard to how I grouped things, I tried to make it forwards compatible with any new entities a modder might require:
Logic - white
Dangerous Stuff - Orange
Atmosphere, lighting - Yellow
Misc - Turquoise
Pathing - Purple
Collectables - Blue
Ammo - Dark Purple
Players / Camera - Green
The sub groupings of stuff have slight variations within those broad colours.
I'll do the Quoth one if you decide to keep the 0-1 colour format, along with some cleanup to make them easier to read.