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