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