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