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