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)(11,14)(12,19)(13,16)(15,21)(17,24)(18,23)(20,22)(25,26,31,29,30,33,37,34)(27,32,36,28,35,39,40,38)(2,5)(3,7)(9,11,13,18)(10,14,16,23)(12,20,21,17)(15,24,19,22)(25,27,30,35)(26,32,33,39)(28,34,38,29)(31,36,37,40)(9,12,13,21)(10,15,16,19)(11,17,18,20)(14,22,23,24)(25,28,37,32,30,38,31,39)(26,27,34,40,33,35,29,36)(1,3,4,7)(2,6,5,8)(10,16)(14,23)(15,19)(22,24)(27,35)(28,38)(32,39)(36,40)(2,5)(6,8)(25,29,31,33,30,34,37,26)(27,28,36,39,35,38,40,32)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.