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