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