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