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