One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10,15,19)(11,16,12,21)(13,18,14,23)(17,20,24,22)(25,26,28,32,29,31,35,38)(27,30,34,37,33,36,39,40)(2,5)(6,8)(9,11,15,12)(10,16,19,21)(13,22,14,20)(17,23,24,18)(25,27,28,34,29,33,35,39)(26,30,32,37,31,36,38,40)(9,12,15,11)(10,17,19,24)(13,22,14,20)(16,23,21,18)(27,33)(30,36)(34,39)(37,40)(1,3,4,7)(2,6,5,8)(9,13,15,14)(10,18,19,23)(11,20,12,22)(16,24,21,17)(26,31)(30,36)(32,38)(37,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.