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