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