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