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