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