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