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