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