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