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