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