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