Leave values as they are

The ptvis.color.IdentityColorConversion class defines a conversion from a value to itself. Therefore, the value must be a color.

import plotly
import ptvis.color


elements = list(ptvis.Element)
colors = ["black" if i % 2 else "white" for i in range(len(elements))]

fig = plotly.graph_objects.Figure()
ptvis.attach_plain_cells(
    fig,
    elements,
    colors=colors,
    color_conversion=ptvis.color.IdentityColorConversion(),
)

plotly.io.show(fig)