SYMPTOM:
In Strategy Web 10.0 to 10.5, when a Visual Insight graph has had its colors changed from the default, the colors do not carry over into a PDF export. Below is a modified graph to have an orange fill color instead of blue:

When exported to PDF, the color has switched back to blue:

CAUSE:
This is a limitation in Strategy Web 10. Exports to PDF do not yet support changes in the default fill color.
ACTION:
Currently this issue has been addressed in Strategy Web 10.6.