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