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