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