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