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)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,26)(27,35)(28,34)(29,31)(30,33)(32,37)(36,40)(38,39) involution — undirected(2,5)(6,8)(9,11,13,18)(10,14,16,22)(12,19,20,17)(15,23,24,21)(26,31)(27,36)(33,34)(37,38)(9,12,13,20)(10,15,16,24)(11,17,18,19)(14,21,22,23)(25,27,29,36)(26,32,31,39)(28,37,30,38)(33,35,34,40)(10,16)(14,22)(15,24)(21,23)(25,28,29,30)(26,33,31,34)(27,37,36,38)(32,35,39,40)(1,3,4,7)(2,6,5,8)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.