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