Fast exhibit reading is usually a sequence, not a talent. Start with the title and axis labels, then identify what the chart is actually comparing, then look for the biggest movement, gap, or outlier before you dive into smaller details.
Many candidates waste time trying to understand everything at once. Instead, ask yourself what decision the exhibit is likely helping you make. That narrows your attention immediately.
You also improve by practicing with lots of varied charts. The more patterns you see, the faster your brain recognizes what matters. You may also find it helpful to read understanding data in case interviews if you want a more structured way to practice this.