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