You can customize the 404 Page as you like. Follow Theme Options > Theme Settings. Here click 404 Page, and the 404-page field will appear.
Custom 404 Style: Switch on to add custom 404 page style.
Page Title: Set Custom Page Title.
404 Page Image: Set Custom 404 Page Image.
Button Text: Set Custom Button Text.
Button Background Color: Set Custom Background Color.
Button Text Color: Set Custom Text Color.
Button Hover Background Color: Set Custom Hover Background Color.
Button Hover Text Color: Set Custom Hover Text Color.
Click Save Changes to save theme options. Click Reset Section to reset only this section. Click Reset All to reset all theme options.