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