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