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)(25,26,30,32,28,33,29,34)(27,35,36,39,37,31,38,40)(2,5)(6,7)(9,11)(10,15)(12,16)(13,18)(14,19)(17,22)(20,24)(21,23)(25,27,30,36,28,37,29,38)(26,31,32,40,33,35,34,39)(9,12,13,15)(10,11,16,18)(14,22,21,20)(17,23,24,19)(26,32)(27,36)(29,30)(31,35)(33,34)(37,38)(1,3,4,8)(2,6,5,7)(10,16)(11,18)(17,24)(19,23)(27,37)(31,35)(36,38)(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.