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