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