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