At the right side of the window, you will see a combo box with a tooltip “Event colors”. You can click on it and select “Pitch”. Now every note should get a different color. Furthermore in the same combo box, you can click at its last option “Setup…” where you can actually change the color for each note. However, the way I understand it, these colors can be setup for the 12 semitones only, i.e. you cannot really have independent colors for different octaves. In the case you describe, probably this won’t matter.