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