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