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