I had a recent experience trying to show a large number of data series by different colours on a plot in Excel. I found the best option for easily distinguishi

I had a recent experience trying to show a large number of data series by different colours on a plot in Excel. I found the best option for easily distinguishing a large number of colours was the monochromatic spectral "rainbow" colours on a black background (there's also a setting to make the data points have a bit of "bloom" aura in the same colour so they look like dots of light). It makes sense from a colour saturation perspective (i.e. signal to noise ratio across the spectrum) that a black background is better. You can pretty much have 10 different colours EDIT: Another benefit is it conveys "sequence/order/distance" information: yellow is between red and green; orange is between red and yellow, etc. It's easy to subdivide and interpret how "close together" two colours are.