Here's the system schematic. It does not show all yard details, such as the engine servicing facilities at Casper. It shows main routes, all sidings, and most spurs. Some other auxiliary track is shown, but not all. That would clutter the schematic terribly, and take a long time to draw!
This schematic is also slightly outdated. Note that it doesn't show Lander, and instead shows a Riverton staging yard. NP East staging (Minneapolis) is shown as three tracks, when in reality there were five. But this diagram does give a good overall sense of the complexity of the layout, and a reasonably accurate indication of length of run on the various lines.
The numbers next to the town names show the maximum train size, in number of 40' cars (excluding the loco and caboose) that can be accommodated in the siding. The small numbers next to the track indicates the length, in inches, of that section of track. For example, the distance from the end of the Worland siding to the beginning of the Basin siding is about 133 inches. Basin is 143 inches long, with the longest passing siding 102 inches.