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