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