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