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