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)(25,26)(27,35)(28,31)(29,33)(30,39)(32,37)(34,40)(36,38) involution — undirected(2,3)(6,7)(12,19)(16,22)(18,23)(20,24)(25,27,31,37)(26,32,28,35)(29,30,36,40)(33,34,38,39)(1,2,5,3)(4,6,8,7)(10,15)(11,17)(16,22)(18,23)(26,28)(32,35)(33,38)(34,39)(9,11,14,17)(10,13,15,21)(12,18,19,23)(16,20,22,24)(25,28,31,26)(27,35,37,32)(29,38,36,33)(30,39,40,34)(1,3,5,2)(4,6,8,7)(9,12,14,19)(10,16,15,22)(11,18,17,23)(13,20,21,24)(25,29)(26,33)(27,30)(28,38)(31,36)(32,34)(35,39)(37,40)(1,4)(2,6)(3,7)(5,8)(9,13)(10,17)(11,15)(12,20)(14,21)(16,23)(18,22)(19,24)(25,30)(26,34)(27,36)(28,39)(29,37)(31,40)(32,38)(33,35) 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.