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)(25,26,29,33,28,32,37,31)(27,34,36,39,35,30,38,40)(2,5)(3,7)(9,10,13,14)(11,18,17,15)(12,21,20,16)(19,22,23,24)(25,27,28,35)(26,30,32,34)(29,36,37,38)(31,39,33,40)(9,11)(10,15)(12,19)(13,17)(14,18)(16,22)(20,23)(21,24)(26,31)(29,37)(30,39)(32,33)(34,40)(36,38) involution — undirected(1,3,4,7)(2,6,5,8)(11,17)(15,18)(19,23)(22,24)(26,32)(30,34)(31,33)(39,40)(2,5)(6,8)(9,12,13,20)(10,16,14,21)(11,19,17,23)(15,22,18,24)(26,32)(30,34)(31,33)(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.