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