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