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