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