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