Classic, colorful, and relaxed is the way to go. Suggestions include:
Khakis or tailored trousers in tan, navy, olive, light gray, or pastels
Button-downs, polos, or dress shirts in pastels, subtle prints, or floral patterns
Sport coats or blazers in light tones or breathable fabrics like linen
Loafers, boat shoes, brown dress shoes, or dressy sneakers
Patterned touches like floral ties, pocket squares, gingham, seersucker, or fun socks