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