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