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