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