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