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