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