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