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