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