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