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