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