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