I looked through the Graflex.org site for past posts on this, but couldn't seem to find anything on this.
I was curious if there was a color coding scheme for the film advance levers on the Graflex Roll Film Holders, I have seen levers in Black, Red, Yellow and Silver on various back sizes and wondered about this.
Thank you in advance for your interest and if someone could direct me to the answer (or a site) I would be most appreciative.

Well, I know some:

Red = RH/8
Blue = RH/10
Green = RH/12

I don't know about the other colors for holders. Graflex made at least 5 replacement dark slide colors: Clear, Red, Blue, Green and Yellow.

My RH-50 is yellow, but I have seen pictures of others with red levers.

What about the RH-20?

From what I have seen in the past the following colors appear to be related to the rollfilm insert lever:
RH-8 Red, RH-10 Black, RH-12 Red, RH-20 Black and lastly the RH-50 Yellow.
However I remember from the early 70's working at a local camera store, and hearing that the levers were color coded by Graflex so the correct size/exposure of the insert could be seen at glance, does this sound right?
As to the colors on the darkslides mentioned in a previous post on this topic, I wondered if they had no real meaning or perhaps was related to the rollfilm insert lever color (but then what about the green, blue and clear colors mentioned)?
Any thoughts on this?

They were listed in the roll holder instructions as "replacement" slides. No particular meaning is described there. I sure didn't know Graflex produced levers with all those colors!