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