The plot of standard error is a shading technique on the contour and 3D graphs found under graph preferences. The darker the shading the higher the standard error at a given coordinate in the factor space. The display can show either standard error or variance depending on the preference setting.
For a more general set of graph tools see Model Graphs - General Information
The standard error plot is available in both Design Evaluation and Model Graphs. The contours will be the same, but the values are different. The evaluation graphs assume a variance of 1. But, after a model is fit, the model graphs version uses the mean squared residual (MSE) estimate from the ANOVA.