Can you tell me where the some of the plumbing runs would be going to?
I disagree that you see the main cutoff anywhere here. Keep looking - all those pipes originate from some other inlet to the house. 

My guess about the red-handle valve is it's there to allow water flow when the softener tank is "offline". That valve should be closed under normal operation. 

I see two "T" joints after the green valve. One has the blue-handle valve on it.  So, to trace a bit, do this:
1) turn the red handle off.
2) Do whatever is needed so water can't pass thru the softener assembly.
3) turn the blue handle off.

Now any outlet/tap/ fixture which still gets water flow probably comes from the T-line on the left.  Once you've identified those, open the blue-handle valve and see what additional items have water flow.   Everything that doesn't have flow at this point probably goes thru the softener leg.