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