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