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