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