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