Jimz picture shows volumes of info if you know what to look for.
Ford (GM, & all of them) bought their wire harnesses from Essex Wire and other vendors. They always kept the correct color codes but in different ways.
For example, if you see R/O on a schematic, that could mean the wire is Red with an Orange trace OR it could be a solid Red wire with an Orange connector. Look back at Jimz bottom picture again. Notice, the Yellow wire has a Yellow connector. That would show on the diagram as simply, 'Y' or 'yellow'.
Yellow wires are always on and not fused. That's where Ray's suggestion comes from. He had a 'mechanic' who caused a fire under his Squarebird dash. Disconnecting either battery terminal would have prevented it.
Take lots of sharp pictures from different angles. There is no such thing as, too many. As described, disconnect the battery, and push the whole switch from behind so as to collapse the spring. Then, loosen the bezel from the driver's seat. Once the bezel is out, the switch will drop into your hand.
Here's the drawing showing Ford group numbers on each part: