The color scheme is the biggest problem of the graphs presentation.
I'm not a coder, but choosing a color in a HSL model (hue, saturation, lightness/luminance) could solve your problem.
For X different colors, divide the Hue scale by X to get the same difference in hue for each color.
I you have more than, say 8 colors, you can get 6 new by selecting a new value for Lightness. And you can again multiply those colors by varying the Saturation.
That way, you will avoid getting too similar colors.
It seems nice, but which is the advantage of being circular?