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