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