One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7,8,5)(4,6)(9,10)(11,20)(12,17)(13,18)(14,23)(15,19)(16,21)(22,24)(25,26,29,33,30,34,28,32)(27,31,37,40,35,38,36,39)(1,3)(2,5)(4,8)(6,7)(9,11,15,12)(10,16,19,24)(13,21,14,22)(17,23,20,18)(25,27)(26,31)(28,36)(29,37)(30,35)(32,39)(33,40)(34,38)(9,12,15,11)(10,17,19,20)(13,21,14,22)(16,23,24,18)(27,35)(31,38)(36,37)(39,40)(9,13,15,14)(10,18,19,23)(11,21,12,22)(16,17,24,20)(25,28,30,29)(26,32,34,33)(27,36,35,37)(31,39,38,40)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.