If you want to change the color of elements within the interface of your Dash app, then you need to use CSS styles, either inline, on the element in particular, or by attaching a style sheet to your app and giving your element you want targeted a className that you have a rule for in the style sheet.
The inline option is much simpler. You can do something like:
html.Div("Some text", style={'color': 'red'})
There are plenty of tutorials on how to use CSS styles to color various types of your HTML.