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