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