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