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