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