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