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