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