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