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