The cable colours do not really matter, what is important is that you connect the terminals the same at both ends.
So using what you have typed: (Bell box connections are on the left)
stb - strobe trigger
hold off - hold off supply
rtn - at return
trg - siren trigger
I would look closely at the hold off and hold off supply terminals, you should find there are two terminals, one +ve the other -ve
I would suggest you use Red for +ve, Black for -ve (same at each end)
For a suggestion (Though as I said it does not matter)
stb - strobe trigger (White)
hold off - hold off supply (Red and Black, see note above)
rtn - at return (Blue)
trg - siren trigger (Yellow)
The green you are left with, coil it up, don't cut it off, and don't connect it to anything.