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