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