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