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