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