This paper presents a control framework for shape control of snake robots for the purpose of locomotion. An advantage of the framework is that it allows the macroscopic shape of a snake robot to be controlled explicitly and intuitively. The framework is based on specifying the desired shape of the snake robot as a continuous shape curve defined by a set of shape control points interconnected by Bézier curves. We propose a novel approach for motion generation in which the shape curve is repeatedly extended according to a desired gait pattern while a virtual snake robot is progressed along the shape curve to retrieve joint reference angles for the physical snake robot. Practical applications of the proposed control framework are exemplified along with simulation results.