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