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