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