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)(11,18)(12,16)(13,22)(14,17)(15,20)(19,24)(21,23)(25,26,31,34,30,29,28,33)(27,35,36,40,37,32,38,39)(1,3)(2,5)(4,7)(6,8)(9,11,14,20)(10,15,17,18)(12,19,13,21)(16,23,22,24)(25,27,30,37)(26,32,29,35)(28,38,31,36)(33,40,34,39)(2,6)(3,7)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,28,30,31)(26,33,29,34)(27,36,37,38)(32,39,35,40)(2,6)(5,8)(11,20)(15,18)(19,21)(23,24)(25,29,31,33,30,26,28,34)(27,35,36,40,37,32,38,39)(9,13,14,12)(10,16,17,22)(11,21,20,19)(15,23,18,24)(25,28,30,31)(26,34,29,33)(27,36,37,38)(32,40,35,39)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.