Here's the answer:
“赤がとても似合いますね”
(aka ga totemo niai-masu ne)
Watch a real native speaker say it:
Here's how it sounds in a textbook:
You could also say:
- 赤がすごく似合いますね
- 赤がとっても似合いますね
Fun fact: the hundreds of thousands of people learning Japanese with Memrise get this phrase correct 94.12% of the time!