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