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