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