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