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