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