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)(11,19,21,15)(12,23,25,38)(13,18)(14,17)(16,24,29,39)(20,33)(22,32,36,28)(26,30)(27,35)(31,40)(34,37)(9,11)(10,15)(12,20)(13,22)(14,21)(16,27)(17,19)(18,28)(23,37)(24,35)(25,34)(26,36)(29,31)(30,32)(33,38)(39,40) involution — undirected(9,12)(10,16,17,29)(11,20)(13,24)(14,25)(15,27,19,31)(18,23,30,38)(21,34)(22,35)(26,39)(28,37,32,33)(36,40)(1,3,5,4)(2,6,7,8)(11,21)(15,19)(20,34)(22,36)(27,31)(28,32)(33,37)(35,40)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.