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