The cables from the control panel are connected to the IO at the back of the monitor like this
I believe CN4 is then routed to the base pcb that looks like this (or a variant without the vga, usb and 3.5mm on the right - that's the non VS model)
The USB A from the gameboard then goes to the USB B on the sub pcb.
Audio and vga from the gameboard goes to the "bottom" VGA and RCA connection
The VGA from the monitor goes to the left VGA connector of the sub pcb
Once all connected it should look like this
If you use the right side connections for another cab, you simply connect a 3.5mm cable from the sub pcb to the second sub pcb.
You connect the USB A from the sub PCB to the USB B of the second sub pcb
Finally the VGA on the right side goes of the sub pcb goes into the second sub pcb
That's how all mine is connected for a VS Naomi setup