First there is probably no commercial modular panel system available, you have to build your own. There are lots of components available for that.
Your controls depend what type of switch motor you use. If you use stall motors like Tortoise or some of the other brands, you would probably want to use a toggle switch. You could use an SPDT to throw the switch and the position of the toggle would indicate direction. If you wanted to add lights (I use LEDs), you could use a DPDT and one side would control the switch motor and the other side the lights. You could use a rotary switch with just 2 or 3 positions. If you do this Rix-Rax makes nice plastic switch covers that look like the prototype electric ones.
If you are using twin-coil machines, you need to use momentary contact switches. The simplest is a momentary push button that you can get from radio shack. It is single pole and you want normally open. There are other suppliers. You could combine this with a rotary to control the lights as I did. You need two buttons for each switch if you use only the buttons. Or you can combine it with a rotary and use only one button.
Recently many people have been doing track diagrams using computer software, including Excel, and printing them on photo paper. then they cut them out and glue them to the panels.
Just some possibilities and thoughts.