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)(25,26,32,34,31,35,29,38)(27,36,37,40,39,33,28,30)(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)(26,33,35,36)(28,32,37,29)(30,38,40,34)(2,6)(5,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,28,31,37)(26,30,35,40)(27,29,39,32)(33,34,36,38)(9,12,14,13)(10,16,17,22)(11,20,21,19)(15,24,18,23)(25,29,31,32)(26,34,35,38)(27,37,39,28)(30,33,40,36)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(25,30,29,33,31,40,32,36)(26,27,38,28,35,39,34,37)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.