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