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