One 40 strip jelly roll will make a lap sized jelly roll race quilt.
If you want to make the quilt shown, I would adjust the size of the block to use the 2.5" strips in the jelly roll. Remember to subtract off the seam allowance (2 x 1/4" = 1/2"), change size (1" finished strips to 2" finished strips, or a 2x multiplier), add seam allowance back. I think I'd get at least 2 or 3 of those jelly rolls.