scroll of silk, cloth presented
幛 centers on a piece of silk or cloth used as a gift or ceremonial scroll, often presented to honor someone.
幛 combines 巾 (cloth) with 章, which likely contributes the sound and may relate to display or pattern, suggesting a cloth presented as a gift or scroll.
The left side 巾 is cloth, and the right side 章 looks like a decorated emblem. Imagine a silk scroll with a beautiful pattern being presented as a gift.
For ショウ, picture a show where a silk scroll is dramatically unveiled: show -> ショウ, and the cloth is presented to the audience.