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