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