I suggest you either copy the star image, change it's colour (e.g with paint.net) and rename it to stars-2.png (or anything) or search Google images for another star with the colour you want and resize it if necessary. Then upload it to "wp-content\themes\davinci\img\css" via FTP
Make sure the image is a transparent background .png file.
Then paste this in Appearance/Customisation/Additional CSS
That IS an easy way, if you have the colouring in skills of a 10 year old. You can download "paint.net" for free and use it to change the colour with the Adjustments/Hue-Saturation tool. Just slide the sliders with your mouse till you get the desired colour. Or you can zoom in and "colour in" the stars with whatever colour you want. Then rename it, upload it and paste in that CSS code. 10 minute job.