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)(15,19)(16,20)(17,23)(18,21)(22,28)(24,26)(25,27) involution — undirected(1,2,3,4)(5,7)(6,9)(8,12)(10,11)(13,14,19,23,18,21,17,15)(16,24,28,22,26,20,27,25)(7,12)(9,10)(13,15,19,14,18,23,17,21)(16,25,28,24,26,22,27,20)(5,7)(6,10)(8,12)(9,11)(13,16,18,26)(14,20,21,24)(15,22,23,25)(17,27,19,28)(7,12)(9,10)(16,26)(20,24)(22,25)(27,28) 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.