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