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