Hi @Peilin you can update the traces and assign a given color to your category:
fig.update_traces({'marker':{'color':'gray'}}, selector={'name': 'year'})
fig.update_traces({'marker':{'color':'gold'}}, selector={'name': 'month'})
If you want to hide the legend entries (which I assume you want to do) you can do it like this:
fig.update_traces(showlegend=False, selector=0)
fig.update_traces(showlegend=False, selector=1)
