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