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