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