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