At first glance of the picture above, I'd say they were indicating how entrenched they still were. Red means operations are still not complete. Blue is that they are sitting ready after a complete mission. Gray means they had no resistance whatsoever, or they are now in hiding.

The different tones of blue are probably because they weren't given a standard # code for the color. They just thought, "blue is blue" and put it up.

I'm basing this off nothing at all, other than what I would do if told to give comms over Twitter banners.