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