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