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