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)(25,26,32,34,31,36,29,39)(27,37,35,40,38,30,28,33)(1,3,4,7)(2,5,6,8)(9,11,14,21)(10,15,17,18)(12,19,13,20)(16,23,22,24)(25,27,31,38)(26,30,36,37)(28,32,35,29)(33,39,40,34)(2,6)(5,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,28,31,35)(26,33,36,40)(27,29,38,32)(30,34,37,39)(9,12,14,13)(10,16,17,22)(11,20,21,19)(15,24,18,23)(25,29,31,32)(26,34,36,39)(27,35,38,28)(30,40,37,33)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(25,30,29,40,31,37,32,33)(26,35,39,27,36,28,34,38)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.