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