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