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