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