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