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