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)(11,17)(12,20)(13,16)(14,19)(15,21)(18,23)(22,24)(25,26)(27,35,37,31)(28,32)(29,34)(30,33)(36,40,38,39)(2,5)(3,7)(9,11)(10,14,16,22)(12,19)(13,18)(15,17,20,23)(21,24)(25,27,29,36,30,37,28,38)(26,31,34,39,33,35,32,40)(11,18)(14,22)(17,23)(19,24)(25,28,30,29)(26,32,33,34)(27,36,37,38)(31,39,35,40)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.