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