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