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