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