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