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