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