You can use this CSS in the custom CSS for the review template.

.wprevpro_t1_DIV_2:before {
color: #695656;
}

You can find hex values here...

https://www.w3schools.com/colors/colors_picker.asp

It should be something like this...

https://www.productreview.com.au/listings/jims-cleaning-group-car-detailing

What are you using?

The best way to find CSS selectors is to right-click on the element > inspect.

There are two ways to download Facebook reviews into the Plugin. 

1) If you want to use the Facebook API method then you would either need to be an Admin on his Facebook page or you could ask him to retrieve the access code and save it into the plugin...

2) You can use the Review Funnel method and all you need is the Facebook page URL. 

That is sort weight. You can use it to show certain reviews before others on a review template.