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