How to change outline color of Material UI Select component (in outlined mode) when dropdown is opened ( currently it is blue )

How do I change the outline color of Material-UI select component outlined variant the right way? Help me change this blue color to red please, I would be really grateful

Image for reference

component for reference code for Reference

<FormControl variant="outlined" fullWidth size={'small'} className={classes.formControl}>
                        <InputLabel id="xAxisDropdown">Select Hardware Platforms</InputLabel>
                        <Select
                           multiple
                           fullWidth
                           labelId="processor"
                           id="processor"
                           value={this.state.selectedProcessors}
                           name={'selectedProcessors'}
                           onChange={this.handleMultiselectChange}
                           label="Select Hardware Platforms"
                           // className={classes.selectBox}
                           classes={{root:classes.selectBox}}
                           renderValue={(selected) => {
                              let names = selected.map(selectedId => {
                                 return this.state.processorList[
                                    this.state.processorList.findIndex(
                                       (processor) => {
                                          return processor.id === selectedId
                                       })
                                    ].nameText
                              })
                              return names.join(', ')
                           }}

                        >
                           {this.state.processorList.map((processor, index) => {
                              return (
                                 <MenuItem key={index} value={processor.id}>
                                    <MainThemeCheckbox
                                       checked={this.state.selectedProcessors.indexOf(processor.id) > -1}
                                    />
                                    <ListItemText primary={processor.selectElement}/>
                                 </MenuItem>
                              )
                           })}
                        </Select>
                     </FormControl>