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