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)(25,26,31,36)(27,37,38,33)(28,39,35,30)(29,40,32,34)(9,11,14,20)(10,15,17,18)(12,19,13,22)(16,23,21,24)(25,27)(26,33)(28,34)(29,30)(31,38)(32,39)(35,40)(36,37)(2,5)(6,8)(25,28,32,33,31,35,29,37)(26,30,34,38,36,39,40,27)(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)(26,34,36,40)(27,30,38,39)(28,37,35,33)(9,13,14,12)(10,16,17,21)(11,19,20,22)(15,24,18,23)(25,30,32,38,31,39,29,27)(26,35,34,37,36,28,40,33)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.