If you use the button module then you type the button text in a field. By default, that text has a single color. If you need a button with text in multiple colors like below, then you can do it as follows:

1. Type your text in a the visual editor in the text area of the module;
2. Give the text the color you want;
3. Select the text and add the hyperlink;
4. Switch to the text editor and add class=”et_pb_button”. That takes on the default Divi button styling, with exception of the text color;
5. This looks as follows in the text editor:

<a class="et_pb_button" href="https://www.deplekkenmakers.nl/wat-wij-bieden/dromenlab/"><span style="color: #000000;">Dromen</span><span style="color: #ffffff;">lab</span></a>Code language: HTML, XML (xml)

If the button gets a wrong background, add a transparent background.

<a class="et_pb_button" href="URL"><span background: transparent; style="color: #000000;">Dromen</span><span style="color: #ffffff;">lab</span></a>Code language: HTML, XML (xml)