Key point
One colour rule
Never make colour the only way to understand a chart. Use colour plus a label, icon, pattern, line style, or direct text.
Your dashboard may be opened on a phone, projector, or low-brightness laptop during judging. The meaning should survive all three.
Why this matters
Many people cannot easily tell red from green, or blue from purple. Even users with normal vision struggle when colours are low contrast or too similar.
A recruiter or judge should not need to guess which line is which. If your chart answers a project question, the colour choices must help that answer.