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