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