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