A smiling face rendered in SVG uses a yellow circle for the head, two black circles for eyes, and a D3-generated arc for the mouth. The React application positions the facial features within a group, translating them to the canvas center. The eyes are drawn with offset coordinates, while the mouth is created using a D3 arc generator with specified inner and outer radii and angular range. The composition is built with React components and D3 v7, using a simple black-and-yellow color scheme.