Hi Sumesh,
Thank you for your interest in Syncfusion Products.
If your intention is to create a Custom Symbol then it can be done by customizing the GroupClass.
The color of nodes(like ellipse,rectangle etc..) can be changed using the code snippet shown below,
ellipse.FillStyle.Color = Color.Red;
The backcolor of textnode can be changed using the code snippet shown below,
textNode.BackgroundStyle.Color = Color.Yellow;
Kindly take a look at the attached sample.
In this sample, I have created a custom symbol by customizing the Group class and have also changed the color of nodes .
Sample:
http://www.syncfusion.com/Support/user/uploads/MySymbol_fc63aa2e.zipLet me know whether this helps you.
Thanks & Regards,
Ramya.