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