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