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