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