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