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