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