With a good tone generator and probe, you may be able to trace the route of the wires from the one end you can find to wherever it runs to. The probe will be able to pick up a signal from the cable even if it is buried in the wall.
Connect the tone generator to the wire, and then use the probe to try and follow the path of the wire as it extends away from the starting point.
Often, the cables have twisted pair wiring, which can reduce the strength of the signal. You may need to experiment a little and connect the red lead of the tone generator to one wire in the cable, and then try the black lead on the other wires in the cable, one at a time. One combination may give you a better signal than another. If you still don't pick up a good signal, try connecting the black lead to something other than a wire in the cable, like the ground pin of a nearby outlet. Be sure you are connecting to the ground wire and NOT the hot or neutral wires!! Sometimes, just leaving the black wire of the tone generator hanging in the air connected to nothing will work.
It possible that the wires for the keypads are run in a daisy chain fashion, from one to another. But then you should see 2 cables at some of the locations.
Can you post pictures of what you see at the door, window, keypad and panel locations? Is the panel location sheetrocked, or is it open studs?