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