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