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