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