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