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