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