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