They are styled like variables:
<dict>
<key>name</key>
<string>Variables</string>
<key>scope</key>
<string>variable, support.variable</string>
<key>settings</key>
<dict>
<key>fontStyle</key>
<string></string>
<key>foreground</key>
<string>#dc322f</string>
</dict>
</dict>
How can I make class properties have a different color?