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