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