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