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