One thing I’ve done (in a pop, not orchestral context) is to use the same basic color for a group of instruments but then use color variations for different instruments within the group. For example my vocals are various shades of green, guitars are red and drums/percussion are orange.
PLE = Project Logical Editor.
Initially it seems much more intimidating than it really is. Here’s how to use it to show & hide Tracks based on the Color Name.
Outside of visibility you also might want to explore some of the other options to color-code Notes in the Key Editor. In the pic you posted if those Notes use different MIDI Channels for each Instrument then you could set it to show each channel in a different color. Below shows the option to color the Notes based on Voice. By default Notes don’t have any Voice assigned, but you (or the Logical Editor, the PLE’s cousin) can freely assign a Voice to a Note. In this example the Notes in the top line are set to Soprano and the line below to Alto. And the poor notes at the bottom have no Voice.
