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