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