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