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