It is going to be wired up pretty much as the 3 phase reverser in the diagram.
Except it looks like you have 120v control voltage instead of 24v.
The control wiring is usually electrically interlocked through N.O. contacts on each side and also the N.C. motor over-loads (mystery device?).
If the wiring is in place, just reverse engineer it by tracing the wires and draw out the schematic.