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