A scatter plot matrix of the Iris dataset displays the relationships between sepal and petal measurements, with points colored by species (setosa, versicolor, virginica). Users click rounded rectangular buttons to select which measurement appears on the x-axis and y-axis, updating the axes and data points accordingly. The visualization uses D3 v5 with SVG rendering, d3.scaleLinear for scales, d3.axisBottom and d3.axisLeft for axes, and d3.csv to load the data, all styled with Comic Sans MS fonts.