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