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