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