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