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