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