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