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