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