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