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