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