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