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