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