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