You will not find a bus company offering legally services from Lausanne to Geneva - within Switzerland, bus travel competing with the railway companies (mostly state owned) still is not allowed, including "cabotage" within Switzerland for international bus trips. So for Lausanne to Geneva it's train - you could find a way using local busses deserving villages, would take around 6h - see www.sbb.ch/en time table "Advanced search" select "Bus" only.
Especially since end of similar restrictions for Germany in 2013 (as last EU country), international bus services in Europe have expanded (some companies using dumping prices). One of the new operators with probably the most important network is Flixbus - interactive map at https://www.flixbus.com/bus-routes#/map - that could allow finding ways to travel by bus from Switzerland to several places in SE France. Other companies probably offer also similar services, some Swiss bus companies for instance high quality, often night trips from Switzerland to vacation resorts in several countries.
Just be aware that long distance bus services in Europe can be kind of chaotic (some cheap in all senses of the word). Trains offer faster, more reliable services in most of Europe.Edited: 14 April 2017, 19:02