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