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