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