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