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