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