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