A cute little bolero or shrug (a la smash or sephorablue) would probably be perfect. Or a regular cardigan - v-necked and fitted at the waist, or a crew neck cardigan, would work well too.
__________________
"Good taste shouldn't have to cost anything extra." - Mickey Drexler
You could try it with a white s/s button down. I tried it on two styles of dresses I have like this one; it worked on one but not on the other, so it's worth a trial.