For an outfit that's pared-down but can be smartened up or dressed down in plenty of different ways, marry a navy pea coat with beige chinos. Complement your look with a pair of brown leather brogues to jazz things up. A look like this will help any gentleman in his forties outshine his younger fellows.
You'll be surprised at how easy it is for any guy to get dressed this way. Just a tobacco overcoat and beige chinos. Finishing off with brown leather brogues is an effortless way to introduce a little classiness to your outfit. This combination is probably exactly what you're looking for as a guy in his 40s.