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