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