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