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