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