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