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)(23,24,26,29,27,30,35,38)(25,31,33,36,32,37,34,28)(3,4,5,6)(7,9,11,17)(8,12,14,15)(10,16,18,22)(13,19,20,21)(25,32)(28,36)(31,37)(33,34)(4,6)(10,18)(13,20)(16,22)(19,21)(23,25,27,32)(24,28,30,36)(26,34,35,33)(29,37,38,31)(7,10,11,18)(8,13,14,20)(9,16,17,22)(12,19,15,21)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.