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