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