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