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