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