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