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