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