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