[Plugin: Contact Form 7] How to change color of send button?

Try creating a custom class around the submit in the form generator:

<p class="contact-submit">[submit "SUBMIT"]</p>

Then, add CSS styles as such:

.contact-submit input{
     width: 100px;
     height: 30px;
     background-color: #000;
     font-size: 13px;
     color: #fff;
     border: 1px solid #fff;
     border-radius: 5px;
}

Hi Josh, have you an idea how to change the standard button for an image?
THANK YOU VERY MUCH if you are able to give me a hand on this. I will really appreciate it.

Try the code from Josh Hardman but replace background-color: #000 with:

background: url(‘https://your-site/your-image-location’);

Something like that should work.