This work proposes a design method for flexible manufacturing systems (FMS). The method reduces the learning curve by helping employees to solve problems related to the design and optimization of the layout, operation and control of FMS, avoiding the drawbacks of current tools. The approach uses Domain Specific Modeling Languages (DSML) for specification of FMS. The paper presents the definition of the DSML and the implementation of the graphical modeling and simulation tool bringing important contributions to development of the domain through the use of constructions from categories theory for DSML specifications. This mathematical basis allows the definition of constraints to avoid supplementary costs and eventual damages through incorrect or incomplete specification of the solutions. By interconnecting with ADOxx of the DSML and tool developed, facilitates access to other analysis and simulation tools like Bee-up, Petri net, better exploration of the design space and extended support for the design activity.