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