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