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