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