I'm guessing you've already played around with it some, so you already know what looks more/less confusing, and I don't know how hard they are to add/remove, but I figure I'll throw out some ideas anyway.
- Put a darker line between ever B and C to denote octaves
- Make all of the "black key" lines the same, or very similar color
- Make "white key" lines also, perhaps a whitish-grey color
- Alternate between darker/lighter grey for the entire background between octaves
If it's easy to do, could you make some screenshots of what these options might look like? Or if it's not, I can just try to draw some lines in MS Paint or something...
edit: I made up the word disoriently