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