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