The strain distributions and of reflection high energy electron diffraction (RHEED) patterns of uncapped pyramidal shape InAs Stranski-Krastanov quantum dots fabricated on GaAs(001) substrate are investigated theoretically. The three dimensional strain anisotropy is computed with an atomistic elasticity approach, using inter-atomic Keating potentials and the strain energy is minimized using the conjugate gradient numerical method. RHEED images are predicted in the framework of the kinematical theory, by taking into account the refraction of the electron beam at the quantum dot/vacuum interface. Clear correlation between RHEED image features and quantum dot structural properties is established. The study stresses the potential of RHEED for future experimental real-time (during growth) detections and deciphering of strain anisotropies in quantum dots.