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