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