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