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