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