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