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