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