A custom color legend displays four ordinal categories—apple, lemon, lime, and orange—as colored circles or squares, rendered with D3 v7's `scaleOrdinal` for domain and range mapping. The legend component supports configurable shapes, spacing, and offsets, using SVG `g`, `rect`, `circle`, and `text` elements. The example demonstrates a reusable legend pattern with enter/merge/exit updates, invoked via `.call(colorLegend.render, {square: false})` to show circular swatches with labels.