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