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