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