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