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)(13,14,18,19)(15,17,22,27)(16,23,26,20)(21,28,24,25)(2,3)(6,9)(10,11)(13,15)(14,17)(16,24)(18,22)(19,27)(20,28)(21,26)(23,25) involution — undirected(1,2,4,3)(13,16)(14,20)(15,21)(17,25)(18,26)(19,23)(22,24)(27,28)(1,3,4,2)(13,17,14,15,18,27,19,22)(16,25,20,21,26,28,23,24)(5,7,8,12)(6,10,9,11)(16,26)(20,23)(21,24)(25,28)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.