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