Hmm. It is trivial to do this, so I took a look.
Here is the current color scheme with different shades of green:
And here is a 120 degree triad scheme:
Not sure if I like the aesthetics, though certainly more discernible.
One of the plans for the future SkookumIDE is to make it so that with the press of a simple hotkey (for example holding down left Ctrl) that all expressions would have their backgrounds with a different color block. This could eventually make SkookumScript optionally look more like a visual programming language (such as Scratch) at glance to make it really obvious how things are grouped together - though still keep it text based.
I like the idea that we could hook up these more discernible colors to the Ctrl key right now to start off visualizations. I'll look into that.
What do you think?