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