Having a rather short CV when applying to grad school is not particularly uncommon. Moreover, I find the general academic trend to focus on the "length" of the CV somewhat misguided. Nobody cares whether your CV is 0.5, 1, or 5 pages per se. That is, padding your CV with unrelated chaff ("worked as barista at Starbucks from A to B", "plays the flute and gitarre on XY level") is not getting your anywhere. What admission commitees etc. care about are mainly two things:
- What relevant experiences do you have for grad school? What specific jobs, service work, special courses, papers, etc. did you do that are relevant?
- What distinguishes you from other candidates? What makes you better / more suitable for grad school than all the other applicants with reasonable undergrad schools and grades?
Note that I am not saying that a CV without undergrad research experience, no previously published papers, no relevant extracurricular activities, and no strong research letters will get you into a great grad school. However, it is important to recognise that the problem here is not the CV document. It is that you do not have those experiences, and no way of formatting your CV will fix these problems.