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