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