Fill objects with color or an image in Keynote on iPad ...
Tap a shape or text box to select it, or select multiple objects.. Tap, tap Style, then tap Fill.. Choose one of the following: A color or gradient designed to go with the theme: Tap Preset, swipe left or right to see all choices, then tap a color. Any color: Tap Color, then tap a color. To preview colors in the object, touch and hold a color, then drag across the grid.