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