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