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