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