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