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)(9,18)(10,15)(11,16)(12,25)(13,17)(14,19)(20,35)(21,28)(22,31)(23,38)(24,33)(26,30)(27,34)(29,36)(32,37) involution — undirected(7,9,13,21)(8,14,17,30)(10,19,12,26)(11,23,24,36)(15,28,25,18)(16,32,33,35)(20,27,37,22)(29,31,38,34)(4,6)(7,10,13,12)(8,15,17,25)(9,19,21,26)(11,22,24,27)(14,28,30,18)(16,31,33,34)(20,36,37,23)(29,32,38,35)(7,11,13,24)(8,16,17,33)(9,20,21,37)(10,22,12,27)(14,29,30,38)(15,31,25,34)(18,35,28,32)(19,36,26,23)(8,17)(14,30)(15,25)(16,33)(18,28)(29,38)(31,34)(32,35) 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.