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