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