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