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