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