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