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