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