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