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