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