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