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