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