Scales to Play Over C7sus4
Every chord is a subset of several scales: any scale that contains all of a chord's tones fits over it. Pick a chord to see the matching scales from its own root, the major keys the chord belongs to, and full fretboard diagrams for every scale on guitar.
A C7sus4 chord contains the notes C – F – G – A#. Any scale that includes every one of those 4 tones fits over it — from the root C, that means C Natural Minor, C Minor Pentatonic, C Blues, C Dorian, C Phrygian, C Mixolydian, C Dorian Bebop, C Mixolydian Bebop and C Spanish. Start with the first scale listed: it is the most common choice, and the others color the same chord tones differently.
C7sus4 is also diatonic to 4 major keys: A# major (relative minor Gm), D# major (relative minor Cm), F major (relative minor Dm), G# major (relative minor Fm). In a song from one of those keys you can also solo with the key's own major scale or its relative minor pentatonic across the whole progression, not just this chord.