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