******* Bobb's has a lot more info for different size speakers, I made this one a few years ago to measure circular cones against each other. Colors are used to see how many of one size it would take to get the same cone area with another size.
And again as was argued before this isn't supposed to be accurate. Of course the cones are smaller than the basket size and I didn't account for the surround, but if I did the ratios would still be roughly the same, therefore the colors are still accurate.