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