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