You can right-click an SF symbol and copy it as an image, type "SVG". Maybe you have to play around with the size a bit. Then you paste the clipboard into a text editor like BB-Edit and - important - remove the line beginning with "<rect...", which defines the background rectangle. Then save your text as "YOUR_ICON.svg".
If you still can't colorize your icon in FileMaker, try my free open source tool "FM SVG Maker" here in the soup. It can not deal with all SVGs, but a lot of them will work.