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