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