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)(13,14,19,23)(15,20,16,21)(17,26,18,22)(24,27,25,28)(6,9)(10,12)(15,24)(16,25)(17,18)(20,27)(21,28)(22,26) involution — undirected(1,2,3,4)(13,15,19,16)(14,20,23,21)(17,24,18,25)(22,28,26,27)(13,16,19,15)(14,21,23,20)(17,25,18,24)(22,27,26,28)(5,7,8,11)(6,10,9,12)(13,17,19,18)(14,22,23,26)(15,24,16,25)(20,28,21,27)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.