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