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