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