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