To choose a theme (color scheme) access Settings by longpressing the key on the bottom left (with the SwiftKey logo). Go to ‘Theme’ and then press ‘Theme’ to set SwiftKey′s theme.
SwiftKey Tablet also has two keyboard different layouts, to allow easy typing with thumbs or fingers. To switch between full and split keyboard just press the layout button (to the left of the spacebar).
You can enable the split layout in landscape on phones by going to to Settings > Theme.