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