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