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