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