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