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