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