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