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)(11,16)(12,14)(13,15)(17,18)(19,23)(20,22)(21,24)(26,30)(31,33)(32,37)(38,39)(9,11)(10,15)(12,16)(13,14)(17,18,20,22)(19,23,24,21)(28,36)(32,37)(34,40)(38,39)(9,10,14,12)(11,15,13,16)(17,19,20,24)(18,21,22,23)(25,26)(27,33)(28,32)(29,30)(31,35)(34,39)(36,37)(38,40)(1,2)(3,5)(4,6)(7,8)(9,12,14,10)(11,15,13,16)(17,18)(19,21)(20,22)(23,24)(25,27,29,35)(26,31,30,33)(28,34,36,40)(32,38,37,39)(1,3,4,7)(2,5,6,8)(9,13,14,11)(10,15,12,16)(17,19)(18,21)(20,24)(22,23)(25,28,29,36)(26,32,30,37)(27,34,35,40)(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.