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