Wiring harnesses
This is so simple, I don't think you need bother. I've had to make up two over the years. Just remember, ('cause I forgot the first time) that you still have to run neutral up to the control panel, even though it's linked to the water inlet solenoid, the drain solenoid, the pump motor and the heater. So - that's three wires going up (P-N-E). Down (assuming no sensors) you've got water inlet solenoid (goes to safety float), drain solenoid, pump motor, fuse block for heater/overheat-protection/heater). That makes seven in all. Which just happens to fit in nicely with the high-current flat ribbons auto-part stores sell for hooking up various things.