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