Set treemap colour by categories in Plotly in Python

Leaving heavy lifting to Plotly Express, once figure is built modify marker_color list

import plotly.express as px
import numpy as np

df = px.data.gapminder().query("year == 2007")
fig = px.treemap(
    df,
    path=[px.Constant("world"), "continent", "country"],
    values="pop",
    color="lifeExp",
    hover_data=["iso_alpha"],
    color_continuous_scale=["#32a852", "#3261a8", "#a83259"],
    color_continuous_midpoint=np.average(df["lifeExp"], weights=df["pop"]),
)
fig.update_layout(margin=dict(t=50, l=25, r=25, b=25))
cm = {
    "Asia": "red",
    "Africa": "yellow",
    "Americas": "white",
    "Europe": "blue",
    "Oceania": "black",
}
fig.for_each_trace(
    lambda t: t.update(
        marker_colors=[
            cm[id.split("/")[1]] if len(id.split("/")) == 2 else c
            for c, id in zip(t.marker.colors, t.ids)
        ]
    )
)