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