By default, the PCA score plot and feature box plot (or violin plot) use the same color schema. However, they may look slightly different, as the PCA plot applies transparency (alpha value) to deal with sample overlaps.
If your data contain less than 18 groups, the color codes are:
"#e6194B", "#3cb44b", "#4363d8", "#42d4f4", "#f032e6", "#ffe119", "#911eb4", "#f58231", "#bfef45", "#fabebe", "#469990", "#e6beff", "#9A6324", "#800000", "#aaffc3", "#808000", "#ffd8b1", "#000075"