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