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