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