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