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)(13,14,17,21)(15,22,24,19)(16,27,18,20)(23,25,28,26)(6,9)(7,12)(13,15,17,24)(14,19,21,22)(16,26,18,25)(20,23,27,28)(2,4)(13,14)(15,23)(16,20)(17,21)(18,27)(19,25)(22,26)(24,28) involution — undirected(2,4)(5,7,8,12)(6,10,9,11)(15,24)(19,22)(23,28)(25,26)(13,16,17,18)(14,20,21,27)(15,25,24,26)(19,28,22,23)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.