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