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