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