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