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