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)(15,16)(17,28)(18,23)(19,27)(20,26)(21,22)(24,25) involution — undirected(2,3)(5,7)(6,9)(8,12)(10,11)(13,15,18,26)(14,20,23,16)(17,25,21,19)(22,24,28,27)(1,2,4,3)(13,16,25,28,18,20,19,22)(14,21,27,26,23,17,24,15)(6,10)(9,11)(13,17)(14,22)(15,25)(16,27)(18,21)(19,26)(20,24)(23,28) involution — undirected(1,3,4,2)(7,12)(9,11)(15,26)(16,20)(17,21)(22,28)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.