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)(11,15)(12,16)(13,14)(17,18)(19,20)(21,23)(22,24)(27,33)(30,34)(35,39)(37,40)(3,8)(5,7)(9,11)(10,15)(12,14)(13,16)(17,19)(18,22)(20,23)(21,24)(25,26,29,32)(27,34,33,30)(28,31,36,38)(35,40,39,37)(9,10,14,13)(11,15,12,16)(17,18,21,23)(19,22,24,20)(25,26)(27,30)(28,31)(29,32)(33,34)(35,37)(36,38)(39,40)(1,3)(2,5)(4,8)(6,7)(9,12,14,11)(10,15,13,16)(17,20)(18,19)(21,22)(23,24)(25,27)(26,30)(28,35)(29,33)(31,37)(32,34)(36,39)(38,40)(1,2)(3,5)(4,6)(7,8)(9,13,14,10)(11,15,12,16)(17,18)(19,20)(21,23)(22,24)(25,28,29,36)(26,31,32,38)(27,35,33,39)(30,37,34,40)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.