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