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)(23,27)(24,28)(25,26)(6,10)(7,11)(13,14)(15,17)(16,18)(19,20)(21,23,26,28)(22,24,25,27)(7,11)(8,12)(14,15)(16,20)(22,25)(23,28) involution — undirected(1,2)(3,4)(5,7,9,11)(6,8,10,12)(13,15,17,14)(16,19,20,18)(21,24)(22,23)(25,28)(26,27)(5,8)(6,11)(7,10)(9,12)(13,16,17,20)(14,18,15,19)(21,25,26,22)(23,24,28,27)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.